Cam grinding machine



Nav. 19, 1957 '0. E. HILL 2,813,318

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. INVENTOR G/VA E. H/LL BY' l ATTORNEY NGV. 19, l O. E. HILL CAM GRINDING MACHINE.

Filed July 27, 1955 8 Sheets-Sheet 2 Figi ATTORNEY Nov. 19, 1957 o. E. HILL 2,813,378

CAM GRINDING MACHINE Filed July 27, 1955 8 SheetS--Sheetl 3 Y JNVENTOR O/vA -4:. H/Lz.

BY I

MM5-w Nov. 19,A 1957 o. E. HILL 2,813,378

CAM GRINDING MACHINE Filed July 27, 1955 INVENTOR E HILL O/ VA A TTOBNEY Nov, 19, 1957 o. E. HILL. 2,813,378

CAM GRINDING MACHINE 4l m 9 .5735-74 575' /78 y 5 f I I 57 'r T Z03- JNVENToR. Z052. @2522 ONA E. H/LL l0- S Z0] "e BY 5?/ zoo/qq ATTO ,eA/E Y Nov. 19, 1957 o. E. HILL 2,813,378

CAM GRINDING MACHINE Filed July 27, 1955 8 Sheets-Shea?I 6 Novv. 19, 1957 o. E. HILL ACAM GRINDING MACHINE Filed July 27, ym55 8 sheets-sheet 7 INVENTOR Mmmm AT-r-OENEY .O/VA E. HILL v Nov. 19, 1957 0, E, HILL 2,813,378

CAM GRINDINGMACHINE K Filed July 27, 1955 8 Sheets-Sheet 8 COUNTER START INVENTOR HIL L nited States Patent CAM GRINDING MACHINE Oiva E. Hill, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application `luly 27, 1955, Serial No. 524,764

13 Claims. (Cl. 51-101) The invention relates to grinding machines, and more particularly to an automatically operated cam shaft grinding machine.

One object of the invention is to provide a simple and thoroughly practical machine for automatically grinding a main bearing and/ or pump eccentric and a plurality of spaced cams on a cam shaft. Another object is to provide an automatic cam grinding machine with a wheel feeding mechanism arranged for imparting a plunge-cut grinding -feed whereby opposed shoulders at opposite ends of a main bearing or pump eccentric may be ground, after which a body feed is imparted to the grinding wheel to grind the cylindrical surface thereof. Another object is to provide an automatically operated steadyrest to support and steady the bearing surface of the cam shaft after it has been ground to a true cylindrical surface.

Another object is to provide an automatically operated grinding wheel truing apparatus which is arranged automatically to true the operative face of the grinding wheel after the main bearing or pump eccentric has been ground and before the cams are ground. Another object is to provide an automatic control for the truing apparatus whereby the operative face of the grinding wheel may be automatically trued after the last cam has been ground when the machine is set-up for grinding cams only.

A further object is to provide an automatic cam grinding machine which may be set up to first grind a bearing or pump eccentric after which successive cams are ground, or may be set up automatically to grind successive cams on `a cam shaft. Another object is to provide an interlock to prevent starting a cam grinding operation before tbc truing operation has been completed. Another object is to provide an interlockA to render the table index control valve inoperative during a bearing, eccentric, or cam grinding operation. Another object is to provide an interlock to prevent movement of the rock bar to an operative position and to prevent an infeeding movement of the grinding wheel before the grinding wheel truing operation has been completed.

Another object is to provide a table-actuated valve to stop the work table in a loading position when the table is moved in one direction to position a main bearing opposite to the grinding wheel, and an interlock valve to render said valve ineffective when the table is indexed in the opposite direction. Other objects will be in part obvious or in part pointed out hereinafter.

the accompanying drawings, in which is shown one of various possible embodiments of the mechanical features of this invention:

Fig. 1 is a front elevation of the automatic cam grinding machine;

Fig. 2 is a vertical sectional view, taken approximately on the line 32-2 of Fig. 1 through the grinding machine showing the wheel feeding mechanism;

Fig. 3 is a vertical sectional View, on an enlarged scale, through the work head, showing the master cam assembly and associated parts;

Patented Nov. 19, 1957 Fig. 4 is a plan view, on an enlarged scale, of the work head with the cover plate broken away and parts shown in section to illustrate the construction;

Fig. 5 is a cross sectional view, on an enlarged' scale, .alten approximately on the line 5 5 of Fig. 4, through the work head showing the driving mechanism for the master cam shaft and the work spindle;

Fig. 6 is a fragmentary front elevation, on an enlarged scale, of the control apron with the cover plate removed and parts shown in section;

Fig. 7 is a fragmentary plan View of the control apron as shown in Fig. 6;

Fig. 8 is a vertical sectional view on an enlarged scale, through the hydraulically operated steadyrest and a portion of the rock bar;

Fig. 9 is a fragmentary rear elevation, on an enlarged scale, of the wheel slide showing the swivelling mechanism therefor in section;

Fig. 10 is a fragmentary plan view, on an enlarged scale, of the wheel feed compensating mechanism having parts broken away and shown in section to clarify the construction;

Fig. 11 is a vertical sectional view on an enlarged scale, taken approximately on the line 11--11 of Fig. 10 through the wheel feed compensating mechanism;

Fig. 12 is a fragmentary horizontal sectional view, on an enlarged scale, taken approximately on the line 12-12 of Fig. 1l, through the overrunning or ball clutch;

Fig. 13 is a fragmentary plan view, on an enlarged scale, of the grinding wheel truing apparatus;

Fig. 14 is a vertical sectional view, taken approximately on the line 14--14 of Fig. 13, through the grinding wheel truing apparatus;

Fig. 15 is a fragmentary horizontal sectional view, on an enlarged scale, taken approximately on the line 15-15 of Fig. 14, through the overrunning or ball clutch;

Fig. 16 is a hydraulic diagram of the actuating mechanisms of the machine;

Fig. 17 is an electrical diagram of the electrical controls of the machine; and

Fig. 18 is a fragmentary diagrammatic View of the rock bar and the actuating limit switch showing an alternative arrangement for control separation of the grinding wheel from the cam being ground.

An automatic cam grinding machine has been illustrated in the drawings having a base 10 which supports a longitudinally movable work table 11 on the usual flat way 12 and V-way 13. The table 11 is arranged so that it may be traversed longitudinally by a manually operable traverse mechanism including a hand wheel 14. This manual traversing mechanism is substantially identical with that shown in the expired patent to C. H. Norton No. 762,838 dated June 14, 1904, to which reference may be had for details of disclosure not contained herein. The manually operable hand wheel 14 is connected to rotate a gear 66 which meshes with a gear 67 mounted on a rotatable shaft 68. The shaft 68 also carries a gear 69 which meshes with a gear 70 rotatably mounted on a shaft 71. The shaft 71 is provided with a gear 72 which meshes with a rack bar depending from the under side of the table 11. A clutch member 74 (Fig. 16) is slidably keyed on the shaft 71 and is provided with clutch teeth which are arranged to mesh with clutch teeth formed on the side face of the gear 70. A hydraulically operated mechanism is provided for actuating the clutch member 74 comprising a cylinder 165 containing a slidably mounted piston 106. A compression spring 107 within the cylinder is interposed between the piston 106 and the right hand end cap 0f the cylinder 185 and serves normally to urge the piston 106 toward the left to hold the clutch member 74 disengaged. During the indexing movement of the table 11 toward the right, fluid under 3. pressure is passed through the pipe 108 into the right hand end chamber of the cylinder 105. This pressure combined with the compression of the spring 106 maintains the clutch 74 disengaged even though the dog 557 momentarily actu-ates the valve 555 and passes fluid under pressure through the pipe 109 into the left hand end chamber of the cylinder 105. When fluid under pressure is passed through a pipe 109 into the chamber formed at the left hand end of the cylinder 105, the piston 106 is moved toward the right to cause a corresponding movement -of the clutch member 74 toward the right to engage the clutch teeth formed thereon with the clutch teeth on the gear 70 so that -a rotary motion of the hand wheel 14 will be imparted through the mechanism above described to traverse the table 11 longitudinally. Similarly when fluid under pressure is passed through a pipe 108 into the right hand end chamber :of the cylinder 105, the piston 106 will be moved toward the left to disengage the clutch.

The table is arranged so that it may be traversed or indexed longitudinally by a power operated mechanism which comprises a hydraulic cylinder 16 (Figure 16) xedly mounted on the underside of the work table 11. The cylinder 16 contains a slidably mounted piston 17 which is connected to a double end piston rod 18, the ends of which are fastened to the base by a pair of brackets 19, only one of which has been illustrated. The hydraulic control mechanism for controlling the admission to and exhaust of uid from the cylinder 16 will be described hereinafter.

The work table 11 serves as a support for a pivotally mounted rock bar 20 which is journalled in a pair of spaced bearings 21 (Fig. 3) and 22 (Fig. 1) and an intermediate bearing (not shown) fixedly mounted on the table 11. The rock bar 20 supports a rotatably mounted master cam or work spindle 23 having la headstock center 24. The spindle 23 is rotatably supported by a pair of spaced bearings 28 and 29 (Fig. 3) carried by the rock bar 20. The rock bar 20 also supports a footstock 25 having a footstock center 26. The centers 24 and 26 serve rotatably to support a cam shaft 27 to be ground having a plurality of integrally lformed cams thereon.

The base 10 also serves as a support for a transversely movable wheel slide 30 which is arranged to slide transversely on a atway 31 and a V-way 32 formed on the upper surface of a wheel slide base 41. The wheel slide base 41 is supported on the machine base 10. The wheel slide 30 supports a rotatably mounted wheel spindle 33 having a grinding wheel 34 mounted on the left hand end thereof (Fig. 1). A motor driven mechanism is provided for driving the wheel spindle 33 and the grinding wheel 34 comprising an electric motor 35 mounted on the upper surface of the wheel slide 30. The motor 35 is provided with a motor shaft 36 carrying a multiple V-groove pulley 37 which is connected by multiple V-belts 38 with a multiple V-groove pulley 39 mounted on the right hand end of the wheel spindle 33 (Fig. l).

Wheel feed The wheel slide 30 is arranged for a transverse feeding movement relative to the base 10 to feed the grinding wheel 34 toward and from the cam shaft 27 to be ground. This mechanism may comprise a rotatable feed screw supported by the base 10. The feed screw 45 meshes with or engages a rotatable feed nut 46 which is rotatably supported by a pair of spaced anti-friction bearings 47 and 4S (Fig. 2). The bearings 47 and 48 are in turn supported in a bracket 49 depending from the underside of the wheel slide 30. The right hand end of the feed screw 45 (Fig. 2) is rotatably journalled in an anti-friction bearing S0 in a slidably mounted sleeve 50a supported by the base 10. The left hand end of the feed screw 45 is provided with a reduced cylindrical end portion 51 which is slidably keyed in a sleeve 52. The sleeve 52 is rotatably journalled in an anti-friction bearing 53.

The cylindrical end portion 51 of the feed screw 4S is connected by a universal joint 54 and a universal joint 55 with the right hand end of a rotatable shaft 56 which is rotatably journalled in bearings carried by the base 10. A gear 57 is mounted on the left hand end of the shaft 56 (Figs. 2 and 16) which meshes with a small gear 58 which is rotatably supported on a shaft 59. A manually operable feed wheel 60 is also rotatably mounted on the shaft 59 and is xedly connected to the gear 58. It will be readily apparent from the foregoing disclosure that a rotary motion of the feed wheel 60 will be transmitted through the mechanism above described to impart 'a rotary motion to the feed screw 45 to impart a corresponding transverse movement to the wheel slide 30 and the grinding wheel 34.

The feed wheel 60 is provided with the old and well known micrometer adjusting mechanism 61 which is arranged to adjust the position of a stop abutment 62 (Fig. 16) relative to the wheel 60. The stop abutment 62 is arranged in the path of a stop surface 63 formed on the upper end of a feed pawl 64. The feed pawl 64 is pivotally supported by a stud 65 on the front of the machine base 10. It will be readily apparent from the foregoing disclosure that a manual rotation of the feed wheel 60 in a counter-clockwise direction will be transmitted through the mechanism above described to impart a rotary motion to the feed screw 45 thereby causing a forward feeding movement of the wheel slide 30 and the grinding wheel 34. This forward feeding movement continues until the abutment 62 moves into engagement with a stop surface 63.

This machine is particularly adapted for rst grinding either a main bearing or a pump eccentric on the cam shaft before grinding successive cams. In such an operation it is desirable to provide a plunge-cut feed whereby the grinding wheel may be fed rapidly up to a grinding position, then at a slower rate for grinding opposed shouldered surfaces adjacent to the portion to be ground. This is preferably accomplished by a hydraulic mechanism comprising a cylinder 340 which is arranged in axial alignment with the feed screw 45 and the slidably mounted sleeve 50a. The cylinder 340 contains a slidably mounted piston 341 which is connected to one end of a piston rod 342, the other end of which is connected to the slidably mounted sleeve 50a. When uid under pressure is passed through a pipe 343, it enters a cylinder chamber 344 formed at the right hand end of the cylinder 340 to cause a rapid approaching movement of the grinding wheel, that is, by movement of the piston 341 toward the left (Fig. 16). During this movement fluid within a cylinder chamber 345 may exhaust unrestricted through a pipe 346, and also through a pipe 347 and a throttle valve 348. By adjusting the throttle valve 348, the rate of the rapid approaching movement of the piston 341 may be readily controlled. The rapid movement of the grinding wheel 34 and the wheel slide 30 continues until the grinding wheel 34 is about to engage the opposed shoulders to be ground at which time the piston 341 closes the port at the end of the pipe 346 after which iluid exhausting from the cylinder chamber 345 must pass through the throttle valve 348. This shoulder grinding feed continues until the piston 341 engages the left hand end of the cylinder 340.

When fluid under pressure is reversed and fluid passes through a pipe 346g, it may pass through a ball check valve 349 into the cylinder chamber 345 to cause a rearward movement of the piston 341 so as to separate the grinding wheel 34 from the work piece being ground. The rearward movement of the piston 341, that is, toward the right (Fig. 16) is cushioned by a dashpot 378. This dashpot mechanism is substantially the same as that shown in the prior U. S. patent to H. A. Silven No. 2,572,529 dated October 23, 1951, to which reference may be had for details of disclosure not contained herein. An adjustable stop screw 379 is provided to determine the extent of movement of the piston 341 toward the right.

A power operated feeding mechanism is provided so that the feed screw may be rotated automatically to cause a movement of the wheel slid e 30 and grinding wheel 34 toward and from the cam shaft 27 to be ground. This mechanism may comprise a hydraulic cylinder 75 (Figs. 2 and 16) which contains a slidably mounted piston 76. The upper surface of the piston 76 is provided with rack teeth 77 which mesh with a small gear 78 which is keyed onto a rotatable shaft 79. The shaft 79 carries a gear 80 which meshes with gear 57 so that movement of the piston 76 will be imparted through the rack 77, the gear 7S, the gear 57 to impart a rotary motion to the feed screw 45. When it is desired to initiate a forward feeding movement of the grinding wheel to grind a cam on the cam shaft 27, iluid under pressure is passed through a pipe 81 into a cylinder chamber 82 to move the piston 76 toward the right (Fig. 16) so as to impart a counterclockwise rotary motion to the feed wheel 60 and to impart a rotary motion to the feed screw 45 to cause a forward movement of the grinding wheel slide 30 and the grinding wheel 34. During this movement fluid within a cylinder chamber 83 may exhaust through a pipe 84.

Similarly when it is desired to cause a rearward movement of the grinding wheel, fluid under pressure is passed through the pipe 84 into the cylinder chamber 83 to cause a movement of the piston 76 toward the left which movement is transmitted through the gears above described to impart a clockwise rotation to the feed wheel 60 and to impart a rotary motion to the feed screw 45 so as to cause a rearward movement of the slide 30 to an inoperative position.

It is desirable to delay the action of the body grinding feed as caused by movement of the piston 76 until the piston 341 is about to move into engagement with the left hand end of the cylinder 340. This is preferably accomplished by a control valve 515 which is preferably a piston-type valve normally held in a right hand end position by a compression spring 516. The slidably mounted sleeve 50a is provided with a depending bracket 517 which supports a rod 518 carrying an adjustably mounted arm 519. In the position of the valve 515 (Fig. 16) fluid passing through the pipe 343 enters a valve chamber 520 and passes through a pipe 521 into the left hand end of a pressure actuated valve 522 to cause the valve to move to a right hand end position. In the position of the valve 522, as shown in Fig. 16, lluid under pressure passing through the passage 487 passes through a pipe 523, through a valve chamber 524, through a pipe 525, through a valve chamber 524, through a throttle valve 499 and also through a ball check valve 503, through a pipe 528, through a throttle valve 499a into the pipe 84 and the cylinder chamber 83 to hold the feed piston 76 in the position illustrated in Fig. 16.

When the valve 522 is moved toward the right, iluid under pressure passing through the pipe 523 is cut olf so that no fluid passes to the feed cylinder 75. As the piston 341 approaches the left hand end of its stroke, the arm 519 engages the stem on this right hand end of the valve 515 to move the valve 515 toward the left so that iluid may exhaust from the left hand end of the valve 522 through a valve chamber 530 and through an exhaust pipe 531 into the reservoir 89. In this position of the valve 522, fluid under pressure passing through the pipe 491 passes through a pipe 49111, through a valve chamber in the valve 522 and through the pipe 81 into the left hand end of the cylinder 75 to start the piston 76 moving toward the right thereby starting a slow rotary motion of the feed screw 45 to impart a body grinding feed to the grinding wheel 34. A throttle valve 98 is provided in the pipe 81 to facilitate controlling the rate of movement of the feed piston 76 in either direction.

When the pin or bearing being ground has been rounded up, it is desirable to apply a steadyrest to the bearing surface to steady the cam shaft being ground during the remainder of the grinding operation on the bearings being ground and also during the grinding of successive cams on the cam shaft 27. As illustrated in Fig. 8 a fluid pressure actuated steadyrest 535 is provided having a slidably mounted member 536 which is provided with a pair of adjustably mounted steadyrest shoes 537 and 538 which are arranged to engage the peripheral surface of the portion of the cam shaft 27 being ground. The steadyrest 53S is slidably supported on a bracket 539 which is clamped onto the rock bar 20. A manually operable adjusting screw 540 is provided to facilitate a transverse adjustment of the steadyrest 535 either toward or from the axis of the cam shaft 27.

A hydraulically operated mechanism is provided for actuating the steadyrest plunger 536 comprising a cylinder 541 which contains a slidably mounted piston 542. The piston 542 is connected to one end of a piston rod 543, the other end of which is fixedly mounted to the plunger 536 so that any movement of the piston 542 will be transmitted to the plunger 536 and the steadyrest shoes 537 and 538. When iluid under pressure is passed through a pipe 544 into a cylinder chamber 545, the piston S42 together with the plunger 536 are moved toward the right (Fig. 8) to move the shoes 537 and 538 into operative supporting engagement with the cam shaft 27. During this movement, fluid within a cylinder chamber 546 formed at the right hand end of the cylinder 541 may exhaust through a needle or throttle valve 547, through a passage 548 and out through a pipe 549. By manipulation of the throttle valve 547, the rate of movement of the steadyrest shoes 537 and 538 into engagement with the surface of the cam shaft 27 may be readily controlled. When fluid under pressure is reversed and passed through the pipe 549, it passes through the throttle valve 547 and also through a ball check Valve 550 (Fig. 16) into the cylinder chamber 546 so that the piston 542 moves at a rapid rate toward the left (Fig. 8) to an inoperative position.

Fluid pressure system A fluid pressure system is provided for supplying iluid under pressure for the several actuating mechanisms of the machine to be hereinafter described. This mechanism may comprise a motor driven Hi-Low pump comprising a low pressure high volume pump and a high pressure low volume pump 86 Which are arranged to draw lluid through a pipe 87 and a pipe 88 respectively from a reservoir 89 and to force iluid under pressure through a pipe 90. A relief valve 91 is provided in the pipe line for returning excess fluid under pressure directly to the reservoir 89 from the pump 86. Similarly a relief valve 92 is provided for allowing excess fluid under pressure from the pump 85 to pass directly to the reservoir 89. A ball check valve 93 is provided between the pump 85 and the pressure pipe 90. In the normal operation of the machine, the pump 86 supplies iluid under high pressure and low volume to the various operating mechanisms of the machine. If there is insulicient volume of iluid in the system for actuating the various mechanisms, the ball check valve 93 opens and the pressure supply in the pipe 90 is supplemented by lluid under low pressure of high volume from the pump 85.

Feed clutch To facilitate setting up the feeding mechanism of the machine when a new grinding wheel is mounted thereon, to set up for different diameters of work pieces, or to facilitate a manual control of the Wheel feed during a grinding operation, it is desirable to provide means for disconnecting the feed wheel 60 from the power actuated mechanism. This is preferably accomplished by means of a clutch mechanism 95 (Fig. 2) which is actuated by a manually operable lever 96 (Fig. 1). This clutch mechanisrn has not been illustrated in detail since it is iden- 7 tical with that shown in prior U. S. Patent No. 2,535,130 dated December 26, 1950, to which reference may be had for details of disclosure not contained herein.

Rock bar actuation The left hand end of the rock bar 20 supports the headstock spindle 23 in a manner hereinbefore described which is contained within a headstoek housing 99. The headstock spindle 23 serves as a master cam spindle for supporting a plurality of master cams 100, one master cam for each cam and each portion on the cam shaft 27 to be `ground. A rotatable slidably mounted master cam follower roller 101 is slidably keyed on a rotatable shaft 102 (Fig. 4). The shaft 102 is journalled in spaced bearings 103 and 104 which are Xedly mounted in the headstock housing 99. During a grinding operation the master cam 100 is maintained in operative engagement with the follower roller 101 by a yieldable means to be hereinafter described so that as the headstock spindle Z3 and the master cams 100 are rotated, the master cam 100 will rotate against the follower roller 101 to impart a controlled working movement to the rock bar 20 so as to generate a predetermined contour on the cam being ground.

Index-master com follower An indexing mechanism is provided for automatically indexing the master cam roller 101 longitudinally on the shaft 102 in timed relation with the longitudinal indexing movement of the table 11 automatically to position the follower roller 101 opposite the master cam 10) corresponding to the cam in the cam shaft 27 to 'oe ground. This indexing mechanism may comprise a dog bar 110 (Fig. which is fixedly supported by a bracket 111 on the base 10. The dog bar 110 is provided with a plus rality of adjustably mounted dogs 112, only one of which has been illustrated in Fig. 5, which are arranged in the path of a star wheel 113 (Figs. 3 and 5). The star wheel is mounted on the end of a rotatable shaft 114, the inner end of which supports a gear 115. The gear 115 meshes with a gear 116 which is mounted on a rotatable shaft 117. The shaft 117 carries a gear 118 which meshes with a rack bar 119 which is slidable longitudinally relative to the headstock housing 99. A yoked member 120 engages the side face of the master cam roller 101 and is xedly mounted to the rack bar 119. This mechanism for indexing the master cam roller 101 is substantially identical with the mechanisms shown in the expired U. S. Patent No. 1,783,755 to Trefethen and Belden dated December 2, 1930, and also expired U. S. Patent No. 2,022,178 to Belden and Silven dated November 26, 1935, to which reference may be had for details of disclosure not contained herein. It will be readily apparent from the foregoing disclosure that when the table 11 is inflexed longitudinally to position successive cams on the cam shaft 27 to be ground, an indexing movement will be imparted to index the master cam roller 101 longitudinally automatically to position the roller 101 in operative relation with the corresponding master cam 100.

A fluid pressure mechanism is provided for rocking the rock bar to and from an operative position. This mechanism may comprise a cylinder 125 which contains a slidably mounted pisto-n 126 connected to one end of a piston rod 127. The other end of the piston rod 127 is connected to a U-shaped frame 128 which is clamped thereon by means of nuts 129 (Fig. 4). An upwardly extending arm 130 is iixedly mounted on the rock bar 20. The upper end of the arm 130 is provided with a pair of horizontally extending arms 131 and 132. A pair of tension springs 133 and 134 are connected at one end to the opposite ends of the U-shaped frame 128. The other ends of the springs 133 and 134 are connected by adjusting screws 135 and 136 respectively to the arms 131 and 132 (Fig. 4). By adjusting the screws 135 and 136, the tension of the springs 133 and 134 may be varied as desired so as to maintain the desired operating pressure between the master cam and the follower roller 101. The arms 131 and 132 on the arm 130 are provided with rollers 142 and 143 respectively which are arranged to be engaged by the U-shaped frame 128 when the piston 126 is moved toward the right (Fig. 16). When fluid under pressure is passed through a pipe 137 into a cylinder chamber 138 to move the piston 126 toward the right, the U-shaped frame 128 will be moved into engagement with the rollers 142 and 143 after which continued movement of the piston 126 toward the right swings the arm in a clockwise direction (Fig. 16) to impart a clockwise movement to the rock bar 20 thereby separating the master cam 100 from the follower roller 101. During this movement of the piston 126, fluid within a cylinder chamber 139 may exhaust through a pipe 140. The adjusting screws and 136 are preferably adjusted so that when the Piston 126 is in its extreme left hand end position (Fig. 16), the tension of the springs 133 and 134 will be suicient to maintain the master cam 100 in operative engagement with the periphery of the follower roller 101 during rotation of the headstock spindle 23 so that the master cam 100 will impart a controlled rocking movement to the rock bar 20 during a cam grinding operation.

As the piston 126 moves toward the right to shift the rock bar 20 to an inoperative position, the U-shaped frame 128 moves toward the right and due to the clearance between the U-shaped frame 128 and the rollers 142 and 143 relieves the tension on the springs 133 and 134 respectively. During movement of the piston 126 and the U-shaped frame 128 toward the right, the frame 128 engages the rollers 142 and 143 respectively and rocks the arm 130 in a clockwise direction (Fig. 16) to rock the rock bar 20 to an inoperative position as illustrated in Fig. 16. By utilizing this construction, the extending and contracting of the springs 133 and 134 is reduced to a minimum. During movement of the piston 126 toward the left, the master cam 100 moves into engagement with the follower roller 101 after which the continued movement of the U-shaped frame 128 toward the left (Fig. 16) separates the frame 128 from the rollers 142 and 143 and increases the tension on the springs 133 and 134 to the desired operating tension. The movement of the piston 126 toward the left continues until the piston 126 engages an adjustable stop screw 141 (Fig. 5) carried by the cylinder head at the left hand end of the cylinder 125.

Work drive A Work driving mechanism is provided for imparting a rotary motion to the headstock spindle 23 and the master cams 100. This driving mechanism is preferably a belt drive in which Gilmer timing belts are utilized which ride upon pulleys cut with grooves which resemble a sprocket. An electric motor 145 is mounted on the upper surface of the headstock housing 99. The motor 145 is provided with a motor shaft 146 having a pulley 147 keyed thereon. The pulley 147 is connected by a belt 148 with a pulley 149' mounted on a rotatable shaft 150. The shaft 150 is rotatably supported on a bracket 151 which is flxedly mounted on the left hand end of the headstock housing 99 (Figs. l and 3). The shaft 150 is provided with a pulley 152 which is connected by a belt 153 with a pulley 154 mounted on a rotatable shaft 155 which is journalled in spaced bearings 156 and 157 (Fig. 4) xedly mounted relative to the headstock housing 99.

An intermediate shaft 163 is provided which is ccnnected by spacer arms 166 and 167 (Figs. 4 and 5) with the shaft 155 and also with a dirven shaft 176 which is axially aligned with the headstoek spindle 23. The shaft 155 is provided with a pulley 160 which is connected by a belt 161 with a pulley 162 keyed onto a rotatable shaft 163. A pair of spaced bearings 164. and 165 carried by a pair of arms 166 and 167 serve as a support for the shaft 163. An idler roller 168 rotatably supported on an adjustable bracket 169 serves to tension thedn'ving belt 161. The bracket 169 is adjustably supported on the side face of the arm 166.

The shaft 163 is provided with a pair of spaced bear' ings 170 and 171 which support the upper ends of a pair of spaced arms 172 and 173 respectively. The lower ends of the arms 172 and 173 are connected by bearings 174 and 175 respectively with the rotatable shaft 176 which is arranged in axial alignment with the headstock spindle 23. The shaft 163 is provided with a pulley 177 which is connected by a belt 178 with a pulley 179 keyed on the shaft 176. An idler roller 180 is rotatably supported on a bracket 181 which is adjustably supported on the arm 173 and serves to facilitate tensioning the belt 178 as desired.

The shaft 176 is operatively connected to transmit a rotary motion to the axially aligned headstock spindle 23. The shaft 176 is provided with an integral flange 135 which is connected by means of a split ring 136 with a ange sleeve 187 which is keyed onto the left hand end of the headstock spindle 23. A friction band or brake 188 surrounds the outer peripheral surface 189 of the sleeve 187 and serves to provide an adjustable braking action which eliminates back-lash in the work driving mechanism above described.

in order to grind tapered faces on the cams of a camshaft, the wheel slide base 41 is pivotally supported so that it may be swiveled in a horizontal plane. A pivot stud 195 (Fig. 9) is xedly supported on the base 10. The wheel slide base 41 is provided with a bearing 196 which mates with or fits on the stud 195.

A hydraulically operated mechanism is provided for imparting a swiveiling movement to the wheel slide base 41 and the wheel slide 30. This mechanism may comprise a cylinder 197 which is xedly mounted on the base 10. The cylinder 197 contains a slidably mounted piston 193 (Figs. 9 and 16). The piston 193 is connected to the end of a piston rod 199, the other end of which is connected to a bracket 200 depending from the underside of the wheel slide base 41.

A stop mechanism is provided for determining the extent of the swivelling movement of the wheel slide base 41 in either direction. This mechanism comprises a stud 201 depending from the underside of the wheel slide base 41. A pair of adjustable stop screws 202 and 2113 are supported by lugs 204 and 205 respectively which are xedly mounted on the base 10. By adjusting the stop screws 202 and 203, the extent of swivelling movement of the wheel slide base 41 in either direction may be readily adjusted.

Fluid under pressure passing through a pipe 206 into a cylinder chamber 207 in the cylinder 197 serves to impart a swivelling movement of the wheel slide base 41 and the wheel slide 30 in one direction which movement is limited by the stud 201 engaging the stop screw 203. During this swivelling movement, fluid within a cylinder chamber 208 may exhaust through a pipe 209.

A control valve 210 is provided for controlling the admission to an exhaust of fluid from the cylinder 197. The valve 210 is a piston type valve having a valve stem 211 which is normally maintained in an uppermost position by means of a compression spring 212. Fluid under pressure passes through a pipe 213 to the valve 210 and in the position of the valve 210 (Fig. 16) passes through the valve 210, through the pipe 206 into the cylinder chamber 207 to move the piston 198 to swivel the wheel slide base 41 until the stud 201 carried by the wheel slide base 41 engages the stop screw 202.

The valve 210 is preferably actuated by and in timed relation with the longitudinal movement of the work table 11. A lever 215 is pivotally supported by a stud 216 carried by a bracket 217 fixedly mounted relative to the base 10. The lever 215 is connected by a stud 218 with the upper end of a plunger 222. The plunger 222 is aligned with the valve stem 211 so that movement of the lever 215 causes a vertical movement of the valve stem 211. The work table 11 is provided with a plurality of adjustable dogs 219, 220 and 221, the lower surfaces of which are arranged to engagey an upwardly extending portion of the lever 215 as the table 11 is moved longitudinally to depress the valve stem 211 so that fluid under pressure from. the pipe 213 passes through the valve 210, through the pipe 209 into the cylinder chamber 208 to swivel the wheel slide base 41 and the wheel slide 30 in the opposite direction. This swivelling movement continues until the stud 201 engages the stop screw 203 to determine the position of the grinding wheel 34 for grinding a taper in the opposite direction on the cam being ground. Fluid exhausting from the control valve 210 passes through a throttle valve 214 by means of which the rate of swivelling movement of the wheel slide base 41 may be readily controlled.

Truz'ng apparatus In case the machine is set up for first grinding a main bearing or pump eccentric having shoulders, there is no reciprocation of the wheel during this plunge-cut operation and it is, therefore, desirable to true the grinding wheel after the bearing or eccentric has been ground and before any of the cams are ground so that a freshly trued surface on the grinding wheel will be provided for the cam grinding operation. In case the machine is set up for grinding only the cams on the cam shaft, it is desirable to true the grinding wheel after all of the cams on a cam shaft have been ground so as to present a freshly trued operative face on the grinding wheel for grinding the cams on the next cam shaft to be ground.

A grinding wheel truing apparatus is provided whereby the peripheral surface of the grinding Wheel may be trued automatically in timed relationship with the cycle of operation, or may be trued continuously when desired. lf it is desired to true automatically during the cycle of operation, either after a main bearing or pump eccentric has been ground and before the cams are ground, or after all the cams have been ground when the table reverses to start an idle stroke toward the left. The truing tool is arranged so that it makes one complete reciprocation across the periphery of the grinding wheel. In case a continuous truing operation is desired, the truing tool is reciprocated continuously until the desired truing operation has been completed. As illustrated in the drawings, a wheel guard 224 surrounds the grinding wheel 34. The wheel guard 224- serves as a support for a truing apparatus 225 (Figs. l, 2 and 14).

rl`he truing apparatus may comprise a truing apparatus base 226 (Fig. 14) which is fastened to the upper surface of the wheel guard 224. A longitudinally traversible slide 227 is mounted on an anti-friction slideway 228 which is supported by the truing apparatus base 226. The slideway 228 is arranged to facilitate a longitudinal traversing movement of the slide 227 in a direction parallel to the axis of the grinding wheel 34.

A hydraulically operated mechanism is provided for traversing the slide 227 longitudinally comprising a cylinder 229 which is formed within the truing apparatus base 226. The cylinder 229 is provided with a slidably mounted piston 230 connected to one end of a piston rod 231. The other end of the piston rod 231 is connected to a bracket 232 which is fastened to the right hand end of the slide 227 (Fig. 13). ln order to facilitate taking up lost motion in the anti-friction slideway 22S, an upper longitudinally extending member 234 of the slideway 228 is supported by the slide 227 and is tapered so that a longitudinal adjustment thereof serves to eliminate lost motion between the antifriction slideway parts. As shown in Fig. 13 a pair of adjusting screws 235 and 236 are provided to facilitate a longitudinal adjustment of the tapered member 234. It will be readily apparent from the foregoing disclosure that 11 by manipulation of the screws 235 and 236, lost motion between the anti-friction slide parts may be adjusted as desired.

rEhe longitudinally movable slide 227 is provided With a transversely extending vertically arranged aperture 237 which serves as a support for a truing tool carrier 238 having a diamond or truing tool 239 mounted at the lower end thereof. The truing tool carrier 23S is supported in spaced bearings 240 and 241 which are carried by the slide 227.

A feeding mechanism is provided for imparting a transverse feeding movement to the truing tool carrier 238 relative to the slide 237. This mechanism is preferably a nut and screw type feeding mechanism comprising a feed screw 242 formed on the upper end of the carrier 23S. A rotatable feed nut 243 meshes with or engages the feed screw 242 and is rotatably supported relative to the slide 227.

A feeding mechanism 244 is provided for actuating the feed nut 243 by and in timed relation with the longitudinal movement of the slide 227. This mechanism comprises a gear 245 which is keyed to the feed nut 243. A small gear 246 meshes with the gear 245 and is rotatably supported by a pawl actuating arm 248 which is rotatably supported on a hub portion of the gear 245. The gear 246 serves as a pawl to actuate the gear 245. The gear 246 is connected by a one-way ball clutch 249 (Fig. l) to the arm 24S. rl`he gear 246 is arranged to rotate freely in a clockwise direction. When the slide 227 moves longitudinally toward the right (Fig. 13), a lug 259 formed integral with the arm 248 moves into engagement with an adjustable stop screw 251 which serves to impart a counterclockwise movement to the arm 248 during which movement the ball clutch 249 holds the gear 246 against rotary motion so that a rotary motion is imparted to the gear 245 thereby imparting a rotary motion to the feed nut 243 to cause a predetermined downward feeding movement to the carrier 233 and the truing tool 239.

When the slide 227 moves toward the left, the lug 25) moves away from the stop screw 251 and the released compression of a spring 252 returns the arm 243 to a central position. When the slide approaches the left hand end of its stroke, a cam face 25.3 formed integral with the arm 243 moves into engagement with an adjustable stop screw 254 which causes a counter-clockwise rotary motion to be imparted to the arm 248 so that the gear 246, being locked against rotation by ball clutch 249, to impart a rotary motion to the gear 245 thereby imparting a predetermined downward feeding movement tothe carrier 238 and the truing tool 239. lt will be readily apparent from the foregoing that a down feeding movement of the truing tool 239 is obtained at each end of the movement of the slide 227. The down feed at the left hand end of the movement of the slide serves to position the truing tool for the next truing cycle. The down feed at the right hand end serves t0 position the truing tool before the return stroke of the truing tool 239 toward the left. The amount of down feed of the truing tool at each end of its stroke may be varied, as desired, by manipulation of the stop screws 251 and 254.

A reversing valve 255 is provided for controlling the admission to and exhaust of fluid from the truing tool cylinder 229. The valve 255 is a piston type valve comprising a valve stem 256. In the position illustrated in Fig. 16, fluid under pressure from the pipe 9G enters a valve chamber 257 and passes through a pipe 258, through a throttle valve 259 into a cylinder chamber formed at the right hand end of the cylinder 229 to cause the piston 239 together with the slide 227 to move toward the left. During this movement, fluid within the cylinder chamber at the left hand end of the cylinder 229 exhausts through a pipe 261), through a throttle valve 261, through the reversing valve 255 and exhausts through a pipe 262. A spring pressed ball 263 serves to normally hold the valve 255 against endwise motion. The valve 255 is actuated 12 toward the right mechanically and toward the left by fluid under pressure.

As illustrated in Fig. 13, the slide 227 is provided with a bracket 264 having an adjustable actuating screw 265 which is axially aligned with the valve stem 256 so that when the slide 227 moves toward the right, the screw 265 will engage the end of the valve stem 256 and shift the valve stem 256 toward the right into the position illustrated in Fig. 16. This arrangement has been illustrated diagrammatically in Fig. 16 by an arm 266 which is connected to move with the piston rod 231.

A pipe 26S is connected to the right hand end 0f the valve 255. When iiuid under pressure is passed through the pipe 268, fluid enters an end chamber at the right hand end of the valve 255 and shifts the valve stem 256 toward the left so as to reverse the ow of Huid between the valve 255 and the cylinder 229. When the valve 255 is in a left hand end position, fluid entering the valve chamber 257 is passed through the throttle valve 261 and also through a ball check valve 269 into the cylinder chamber formed at the left hand end of the cylinder 229 to move the piston 230 together with the slide 227 longitudinally toward the right.

When pressure is passed to the left hand end of the cylinder 229, it also passes through a pipe 27) into the right hand end of a cylinder 271 of a wheel feed compensating mechanism to be hereinafter described. The cylinder 271 contains a slidably mounted piston 272 which is fastened to the right hand end of a piston rod 273 (Fig. 16). A compression spring 274 surrounds the piston rod 273 and is interposed between the piston 272 and a left hand end cap 275 on the cylinder 271. The function of this compensating cylinder will be hereinafter described.

A control valve 280 (Fig. 16) is provided to facilitate interlocking the truing apparatus with the rock bar and the wheel feeding mechanism so that a grinding operation cannot be initiated until the truing operation has been completed. This valve is a piston type valve comprising a valve stem 281. A compression spring 282 is provided normally to hold the valve 280 in a right hand end position. When the slide 227 is traversed toward the left, an adjustable actuating screw 283 (Fig. 13) carried by the bracket 232 engages the end of the valve stem 281 and shifts the valve 286 into a left hand end position as illustrated in Fig. 16. The actuation of the valve 29.0 shown diagrammati'cally in Fig. 16 in which a bracket 284 carried by the piston rod 231 serves to engage the valve stem 281 to shift the valve 280.

This interlock is preferably accomplished by connecting the valve 446 by a pipe 443 with a valve chamber 444 in the valve 280. A pipe 454 is connected between the valve chamber 444 and an end chamber 466 formed in the left hand end of the valve 352. When the truing apparatus has made one complete reciprocation of the truing tool 239 across the periphery of the grinding wheel 34, the valve stem 281i is shifted toward the left into the position illustrated in Fig. 16 so that liu-id under pressure within the pipe 443 passes into the valve chamber 444 of the valve 280 and passes through the pipe 454 into the end chamber 466 at the left hand end of the valve 352 to shift the valve 352 into a right hand position and also uid under pressure from the valve 446 passes through the throttle valve 452 and the ball check valve 453 into an end chamber 497 to shift the valve 353 toward the right. ln this position of the valve 352 uid under pressure in the pipe 9i) enters the valve chamber 489 of the valve 352 and passes through the pipe 491, through the pipe 14) into the cylinder chamber 139 to move the rock bar piston 126 toward the left (Fig. 16) thereby shifting the rock bar to an operative position with the master cam in operative enga v. ith the follower roller 101. The rate of shifting the valve 352 toward the right is controlled by fluid exhausting from the right hand end of the valve, through a throttle valve 467 into the pipe 442. A ball check valve 468 is provided to allow fluid to bypass around the throttle valve '13 467 when iiuid under pressure is passed through the pipe M2 into the right hand end chamber of the valve 352 to shift it toward the left.

At the same time lluid under pressure passing through the pipe 491 passes through a throttle valve 98, through the pipe 81 into the cylinder chamber 82 formed at the l-eft hand end of the grinding wheel feed cylinder 75 to start the piston 76 moving toward the right (Fig. 16) so as to initiate an infceding movement of the wheel slide 30 and the grinding wheel 34. Similarly by manipulation of the throttle valve 98 the rate of the return movement of the feed piston 76 toward the left may be regulated as desired. A ball check Valve 503 serves to facilitate a rapid admission of fluid .to the feed cylinder 75 when the ow of fluid is reversed to cause a rapid rearward movement of the Wheel slide 30 and the grinding wheel 34.

When the machine is set-up to rst grind a main bearing or pump eccentric having opposed shouldered faces before grinding the cams, it is desirable to true the grinding Wheel after the bearing or eccentric has been ground. As shown in Fig. 16, the valve 587 is closed and the valve 584 opened so.that after a main bearing or pump eccentric has been ground and the table 11 starts moving toward the left, a dog 582 depresses the valve 580 so that iiuid under pressure passes through the pipe 583, through the pipe 585, through the selector valve chamber 287, through the pipe 268 to shift the valve 263 toward the left to initiate a truing cycle.

If it is desired to set up the machine for grinding only the cams on the cam shaft, it is desirable to true the grinding wheel after the last cam on the shaft has been ground. In this case the valve 584 is closed to render the valve 580 inoperative and the valve 587 is opened so that when the reversing valve 380 is shifted at the right hand end of the table stroke after the last cam has been ground, fluid will be passed from reversing valve 380 through :the pipe 376, through the valve chamber 287 in the selector valve 285, through the pipe 268 into the right hand end `of the valve 255 to initiate a truing cycle.

A manually operable selector valve 285 is provided to facilitate automatic actuation of the wheel truing mechanism in timed relation with the grinding cycle, or a continuous reciprocating of the truing tool or to render the the truing apparatus inoperative as desired. In the position of the selector valve 285 (Fig. 16) when fluid under pressure is passed through a pipe 376, it passes through a passage 287 in the selector valve 285 to shift the reversing valve 255 into a left hand end position thereby starting a truing cycle. The truing tool 239 together with the slide 227 is normally in a left hand end position and when a truing operation is initiated, the truing tool 239 together with the slide 227 makes one complete reciprocation, that is, to pass the truing tool across the operative face of the grinding Wheel 34 twice.

If a continuous actuation of the truing tool is desired, the selector valve 285 is turned in a counter-clockwise direction so that fluid under pressure passing through the pipe 90 enters a Valve chamber 288, passes through a pipe 289, through a passage 290 in the selector valve 285 and passes through the pipe 268 into the right hand end of the valve 255 to move the valve 255 into a left hand end position. In this position of the parts, uid under pressure passing through the pipe 90 enters the valve chamber 257 and passes into the left hand end of the cylinder 229 to traverse the truing tool 229 together with the slide 227 toward the right. As soon as this movement is started, the actuating screw 283 (Fig. 13) moves away from the valve stem 281 so that the released compression ,of the spring 282 shifts the valve 280 toward the right thereby cutting off fluid under pressure from the pipe 90 so that it cannot enter the valve chamber 288. Movement of the truing tool slide 227 toward the right continues until the stop screw 265 engages the valve stern 256 and shifts the valve 255 toward the right into the position, shown in Fig. 16, so that fluid under pres'- sure entering the valve chamber 257 passes through the pipe 258 and the throttle valve 259 into the right hand end chamber of the cylinder 229 to start movement of the truing tool slide 227 toward the left. Movement of the slide 227 toward the left continues until the stop screw 283 engages the valve stem 281 and again shifts the valve 280 into a left hand end position as shown in Fig. 16. In this position of the valve 280 iiuid under pressure is again passed through the pipe 268 into the right hand end chamber of the valve 255 to shift the valve 255 into a left hand end position so as to start a transversing movement of the truing tool slide 227 toward the right. The truing apparatus slide 227 reciprocates continuously to transverse the truing tool 239 across the operative face of the grinding Wheel 34. The continuous truing operation continues as long as the selector valve 285 is positioned so that fluid may pass from the valve 280 through .the passage 290. When it is desired to stop the continuous truing operation, the selector valve 285 is turned to the position illustrated in Fig. 16.

When it is desired to render the Vtruing apparatus inoperative, the selector valve 285 is rotated so that fluid may exhaust from the right hand end chamber of the valve 255, through the pipe 268, through a passage 291 in the selector valve 285 and exhaust through a pipe 292. In this position of the selector valve, Huid under pressure is maintained in the chamber formed at the right hand end of the cylinder 229 to hold the slide 227 together with the truing tool 239 in a left hand end position.

A wheel spindle reciprocating mechanism is provided Within the wheel slide 30 for reciprocating the wheel spindle 33 axially within its bearings during a grinding operation. This mechanism has not been illustrated since it is identical with that shown in the prior U. S. Patent No. 2,237,496 to G. T. Muskovin dated April 8, 1941, to which reference may be had for details of disclosure not contained herein. It is desirable to automatically stop the reciprocation of the grinding wheel spindle 33 during a truing operation. This is preferably accomplished by a hydraulically operated mechanism, shown diagrammatically in Fig. 16. At the start of a truing cy-cle, when the valve stem 281 of the valve 280 moves toward the right, fluid under pressure from the pipe entering the valve chamber 28S may pass through a pipe 570, a valve 566, a pipe 295, through a throttle valve 296 into a cylinder chamber' 297 formed in the left hand end of a cylinder 298. The cylinder 298 contains a slidably mounted piston 299 Which is connected to one end of a piston rod 300. A compression spring 301 surrounding the piston rod 300 and interposed between the piston 299 and the right hand end of cylinder 298 serves normally to hold the piston 299 in a left hand end position so as to facilitate an axial reciprocation of the Wheel spindle during a grinding operation. When fluid under pressure is admitted to the cylinder chamber 297, the piston 299 is moved toward the right so -that the piston rod 300 operates to render the wheel spindle reciprocating mechanisrn inoperative during a grinding wheel truing operation.

In grinding a main bearing or pump eccentric, it may be desirable to swivel the wheel slide 30 to a central position so that the axis of the Wheel spindle 23 is parallel to the axis of the cam shaft 27 being ground so that a cylindrical face will be ground upon the portion being ground. This is preferably accomplished by a hydraulically operated mechanism comprising a cylinder 590 (Fig. 9) which is mounted on the rear of the base 10 of the machine. The cylinder 590 contains a slidably mounted piston 591 which is normally held in an uppermost position by a compression spring 592 contained within the lower portion of the cylinder 590. The piston 591 is provided with a piston rod having an arrow-pointed end 593 which is arranged to engage a correspondingly shaped asis-,S78

notch 594 formed in a bar 595 which is fiXedly mounted and depends from the under side of the wheel slide base 41. The pipe 108 is connected with a pipe 596, and a ball check valve 661 which is connected by a pipe 599 with a cylinder chamber 598 formed at the upper end of the cylinder 590 (Fig. 9). The pipe 108 is also connected by a manually operable shut-off valve 600 with the pipe 599 which serves to facilitate rendering the piston and arrow-point inoperative when desired by trapping uid within the cylinder chamber.

When uid under pressure is passed through the pipe 108 during the intermittent indexing of the table 11 t0- ward the right while grinding successive cams, fluid under pressure may pass through the ball check valve 601 and also through the valve 660 if it is opened to admit fluid to the cylinder chamber 598 to move the arrow-point 593 out of engagement with the notch 594 and to hold it out of engagement during the entire movement of the table toward the right. When the table is reversed at the right hand end of its stroke the pipe line 108 is opened to eX- haust thereby releasing the compression of the spring 592 so that the arrow-point 593 moves into engagement with the bar 595. The parts remain in this position during the remainder of the idle stroke of the table toward the left. After the finish ground cam shaft has been removed from the machine and a new cam shaft inserted thereinstead, the next cycle is started by shifting the cycle start lever 416 which serves to pass fluid under pressure from the valve 21 to move the valve 352 toward the right so that fluid under pressure passes through the pipe 491 through the pipe 213, through the valve 210, through the pipe 206 into the cylinder chamber 207 to move the piston 198 toward the left (Fig. 16) to swivel the wheel slide base 41 in a counterclockwise direction. During this movement the released compression of the spring 592 moves the arrow-point 593 into operative engagement with the notch 594 to center and hold the wheel slide in a central position during the bearing or eccentric grinding operation. The arrow-point 593 remains in engagement with the notch 594 during grinding the main bearing or eccentric and also during the movement of the table 11 from this position to the extreme left hand end position. When the table reverses and the table starts moving toward the right, the reversing valve 380 passes fluid under pressure through the pipe 376 and the pipe 108, through the ball check valve 661 into the cylinder chamber 598 to move the arrow-point 593 from operative engagement v/ith the notch 594 so that the wheel slide base is free to swivel as governed by the swivelling mechanism previously described.

When a manual feeding adjustment of the truing tool 239 is desired, the selector valve 285 is rotated in a counter-clockwise direction (Fig. 16) so that fluid in the pipe 268 may exhaust through the passage 291. During normal operation of the truing apparatus, the ball clutch 249 is clamped in a fixed relationship with the arm 248 by means of a sleeve 305 and a hollow bolt 306 having an actuating handle 307. When it is desired to manually feed the truing tool 239, the handle 307 is turned to release the nut 306 and the sleeve 38S thereby unclamping the ball clutch 249 from the arm 248. A manually operable feed wheel 398 may then be rotated. The feed wheel 38S is mounted at the lower end of a rotatable shaft 309 (Fig. 14) lthe upper end of which is provided with a gear 310 which meshes with the feed gear 245. A serrated wheel 311 together with a spring pressed plunger 312 are provided to hold the gear 310 against rotary motion except when actuated by the arrn 248 or the manual feed wheel 398. lt will be readily apparent from the foregoing disclosure that a rotary motion of the feed Wheel 388 will be imparted to cause a vertical adjustment of the truing tool 239 together with the carrier 238. The direction of rotation of the feeding wheel serves to determine whether an up or a down feeding adjustment of j the truing tool 239 is obtained.

lA wheel feed compensating mechanism is provided automatically to advance the grinding wheel slide by an amount equal to the down feed of the truing tool 239 at each actuation thereof. This mechanism comprises a vertically arranged shaft 315 (Fig. 2) which is rotatably supported on the wheel slide 30. The lower end of the shaft 315 is provided with a worm 316 which meshes with a worm gear 317 formed on the outer periphery of the feed nut 46. The upper end of the shaft 315 is supported by anti-friction bearings 318 (Fig. 11) which are supported in fixed relationship with the wheel slide 30. A gear 319 is keyed onto the upper end of the shaft 315. An oscillatable pawl carrying arm 320 is rotatably supported by a bearing 314 on the upper end of the shaft 315. A gear 321 (Fig. 11) keyed onto a stud 322 which is rotatably supported on the arm 320 meshes with the gear 319. A one-way ball clutch 323 is interposed between the arm 320 and the stud 322 so that the gear 321 is arranged to rotate freely on the arm 320 when the arm is moved in a counter-clockwise direction so that the gear 321 rolls idly on the gear 319. The ball clutch 323 is arranged so that when the arm 320 (Fig. 10) is moved in a clockwise direction, the gear 321 is locked to the arm 320 and thereby imparts a rotary motion to the gear 319.

The gear 321 together with the stud 322 and the ball clutch 323 are preferably supported by a pivotally mounted bracket 324 which is pivotally connected to the arm 320 by means of a stud 325. An adjusting screw 326 is provided to facilitate adjusting the meshing of the gear 321 relative to the gear 319. A clamping screw 327 is provided to facilitate locking the bracket 324 in adjusted position relative to the arm 320.

An adjustable stop screw 328 is provided on a bracket 329 which is fixedly mounted relative to the wheel slide 30. The stop screw 328 serves to limit the stroke of the arm 320 in a clockwise direction thereby limiting the compensating feed of the wheel slide. It will be readily apparent from the foregoing disclosure that by manipulation of the stop screw 328 the extent of compensating feed may be varied as desired so that the grinding wheel slide 30 will be advanced by an amount equal to the down feed of the truing tool 239. The piston rod 273 (Fig. 10) is connected by a stud 330 with one end of a link 331. The other end of the link 331 is connected by a stud 332 with the pawl arm 320. When fluid under pressure is passed through the pipe 270 to start a traversing movement of the truing tool 239 toward the right, fluid will be passed into a cylinder chamber formed at the right hand end of the cylinder 271 to move the piston 272 toward the left (Fig. 10) against the compression of the spring 274 thereby rocking the pawl arm 320 in a clockwise direction to transmit a compensating rotary motion to the feed nut 46. A single compensating adjustment of the wheel feeding mechanism is made at the start of each truing cycle. The amount of compensating feed is equal to the sum of the down feed at the right hand end of the truing tool stroke and at the left hand end thereof.

A holding pawl mechanism is provided to prevent counter-clockwise motion of the compensating feed gear 19. This mechanism comprises a small gear 335 which meshes with the gear 319 (Figs. l0 and l1). The gear 335 is keyed onto a stud 336 rotatably supported by a bracket 337 which is iixedly mounted relative to the wheel slide 30. A one-way ball clutch 338 is interposed between the stud 336 and bracket 337 which is arranged to allow the gear 335 to rotate freely in a counter-clockwise direction when the feed gear 319 is rotated to impart a compensating feed to the wheel slide. The one-way clutch 338 serves to lock the gear 335 to the bracket 337 so that the gear 319 cannot be rotated in a counterclockwise direction. It will be readily apparent from the foregoing disclosure that the gear 335 serves as a holding pawl to facilitate rotation of the gear 319 in one direction only.

A control valve unit 350 is provided comprising a fluid operated reversing valve 351 which controls the direction of movement of the work table 11, a uid actuated control valve 352 which serves to control the admission of fluid to and from the wheel feed and rock bar cylinders and also serves ras a backlash eliminator valve for the wheel feed, and a lluid operated control valve 353 which serves to provide a rock bar dwell and. also a table cushioning. The reversing valve 351 (Fig. 16) is a iluid pressure operated valve which is normally held in a central or neutral position by a pair of balanced compression springs in the opposite ends thereof.

When lluid under pressure is passed through -a pipe 354, through both the throttle valve 372 and the ball check valve 373 into an end chamber 35S in the valvc 351, the valve 351 is shifted into a right hand end position. During movement of valve 351 toward the right, lluid within an end chamber 374 exhausts through a throttle valve 375 into the pipe 376. The throttle valve 375 serves to control the rate of shifting the valve 351 toward the right. A ball check valve 377 between the end chamber 374 and the pipe 376 serves to allow substantially unrestricted ow of fluid from the pipe 376 into the end chamber 374 when the flow of fluid under pressure is reversed. IIn the right hand end position of the valve 351 huid under pressure from the pipe 90 enters a valve chamber 356 and passes out through a pipe 357 into a cylinder chamber 358 formed at the right hand end of the table cylinder 16 to start movement of the table 11 toward the right. During this movement of the table 11 fluid within a cylinder chamber 353` exhausts through a pipe 360, through a throttle valve 361 by means of which the rate of movement of the table toward the right may be regulated. Fluid passing through the throttle valve 361 passes through a pipe 363. A ball check valve 362 is provided between the pipe 360 and the pipe 363 so that when iluid under pressure is passed through the pipe 363 to cause movement of the table 11 toward the left, fluid may pass substantially unrestricted through the ball check valve to facilitate a rapid movement of the table 11 during its idle stroke.

Fluid exhausting through the pipe 363 enters a valve chamber 364 in the valve 351 and passes out through a pipe 365 into a valve chamber 366 in the valve 353. Fluid entering the valve chamber 366 passes out through a pipe 367, through a ball check valve 368 and exhausts through a pipe 369. This allows the table 11 to travel at a normal indexing rate as controlled by the throttle valve 361. When the valve 353 is shifted toward the right as will be hereinafter described, the pipe line 367 is cut oif so that fluid exhausting into the chamber 366 must exhaust through a pipe 370 and through a throttle valve 371, through the ball check valve 36S and exhausts through the pipe 369. This throttling arrangement serves to provide a slow-down in the indexing movement of the table 11 as it approaches the next grinding position.

A manually operable table actuated rotary-type reversing valve 380 is provided for controlling the direction of how of fluid through the pipe 569 and the pipe 376. T he valve 330 comprises a valve rotor 381 which may be actuated manually by means of a control lever 332 or actuated automatically by a pair of adjustable table dogs 333 and 384 which are adjustably mounted on the work table 11. When the table 11 moves toward the right and approaches its extreme end position, the dog 333 engages a lug 385 which is ixedly mounted relative to the valve rotor 381 to shift the valve rotor 381 in a counter-clockwise direction. Similarly at the other end of the table stroke as the table approaches its left hand end position, the table dog 384 engages a lug 386 tixedly mounted relative to the valve rotor 381 to rock the valve rotor 381 in a clockwise direction into the position illustrated in Fig. 16.

The mechanism above described for actuating the reversingvalve 380 is diagrammatically shown in Fig. 16. As shown in Fig. 6, the lever 389 is mounted at the upper end of a vertically arranged rotatable shaft 396. A short lever arm 391 is mounted on the lower end of the shaft 390. The arm 391 is connected by a stud 392 with one end of a link 393. The other end of the link 393 is connected by a stud 394il with a snap-over or load and tire mechanism 395 (Fig. 6) to actuate the rotor 381 of the valve 380. When the table 11 reaches the right hand. end of its stroke, the dog 383 engages the lug 385 to rock the reversing lever 332 in a clockwise direction (Fig. 7) which serves through the mechanism above described to impart a rotary motion to the valve rotor 381 in a counter-clockwise direction (Figs. 6 and 16) during which movement the load and fire mechanism 395 engages an actuating roller 396 of a normally closed limit switch LS6 to open the switch. The function oi the switch LS6 will be hereinafter described.

An interlock is provided so that the table indexing movement cannot be started until the rock bar 2i) iis rocked to an inoperative position to separate the master cams from the follower roller 101. This interlock preferably comprises a piston type valve 400 (Fig. 16) having a valve piston 4111 which is normally held in an uppermost position by a compression spring 4132.. The valve stem 401 is provided with a pair of spaced integral valve pistons which form a valve chamber The rock bar 20 is provided with an arm 404 which is arranged to engage and depress the valve stem 401 into the position illustrated in Fig. 16 when the rock bar Zit is rocked to an inoperative position.

A pipe 405 is connected between the pipe and the valve 46?. Similarly a pipe 4.06 is connected between the pipe 137 and the valve 411i). A pipe 407 is connected between the valve 4th) and a cycle start valve 410 to be hereinafter described. The valve 400 (Fig. 16) is shown depressed by the arm 434 since the rock bar 20 is rocked to an inoperative position. The rock bar is also provided with an arm 108 (Fig. 16) which is arranged to open a normally closed limit switch L83 when the rock bar 20 is rocked to an inoperative position. The rock bar 20 is also provided with an adjustable arm 433e (Figs. 16 and 18) which is arranged to actuate a limit switch L52 during each oscilation of the rock bar 20. The limit switch LS2 is operatively connected to impart an impulse to the electric counter or counters.

In the grinding of cams on a cam shaft, it may be desired to separate the cam being ground from the grinding wheel when the nose of the cam is in Contact with the grinding wheel so that any mark on the cam caused by the separating movement will occur on the nose of the cam. In such a case a normally closed limit switch L82 (Fig. 16) may be employed which is opened when the nose of the master cam approaches engagement with the follower roller which serves at count-out of the electric counter to separate the grinding wheel from the cam being ground when the nose or high point of the cam being ground is in contact with the grinding wheel.

Similarly in the grinding of cams, some users may prefer to have the cam being ground and the grinding wheel separate on the base circle of the cam being ground so that any mark left due to the separating movement will occur on the base circle of the cam. ln this case the normally closed limit switch as shown in Fig. 16 is replaced by a normally open limit switch L82 (Fig. 18) which is actuated by the arm litSa each time the base circle of the cam approaches engagement with the master cam roller so that at count-out of the electric counter the separation of the grinding wheel from the cam being ground will occur when the base circle o the cam being ground is in contact with the grinding wheel.

In case it is desired to separate the cam being ground from the grinding wheel when the nose or high point ol the cam is in engagement with the grinding wheel, the normally closedv limit switch LSZ, as shown in Fig. 1 is utilized to control the actuation of the count coils oi 19 the counters 481 and/or 482 to control the operation of the wheel and work. In case this set-up is utilized Huid under pressure from the valve chamber 486 of the valve 352 passes through the passage 487, through the valve 522, through the ball check valve 503 through a manually operable Valve 49911 and through the pipe 84 into the cylinder chamber S3 rapidly to move the piston toward the left to move the grinding wheel rapidly to an inoperative position. At this time the valve 353 is in a right hand end position and gradually moves toward the left as controlled by the throttle valve 452. As soon as the port at the end of the passage 487 is uncovered fluid under pressure from the valve chamber 486 passing through the passage 487 enters the valve chamber 488 in the valve 353 and passes through the pipe 137 to the cylinder chamber 138 to move the piston 126 toward the right into the position illustrated in Fig. 16 thereby rocking the rock bar 20 to an inoperative position. In this case the movement of the rock bar to an inoperative position is delayed in its action and the delay thereof may be regulated and controlled by manual adjustment of the throttle valve 452. With this arrangement of the parts, the grinding wheel is rapidly separated from the cam being ground while the nose of the cam is in operative engagement therewith after which the rock bar 29 is rocked to an inoperative position.

A ball check valve 503m is connected in the pipe line 84 between the ball check valve 503 and the cylinder 75. A bypass around the ball check valve 503a is provided which is controlled by a manually operable valve 499.4. A pipe 137a is connected between the pipe 137 and the pipe 84. A ball check valve 503b is provided in the pipe line 137a so that iluid may pass only in the direction toward the cylinder 75. A shut-olf valve 4991) is provided in the pipe line 137a between the pipe 137 and the ball check valve 503k. When the separation of the cam and grinding wheel is controlled as above described, the valve 499!) is closed and the valve 499 opened so that fluid under pressure may pass around the ball check valve 503 into the cyflinder chamber 83.

In case it is desired to separate the grinding wheel from the cam being ground while the base circle of the cam is in operative engagement therewith, a normally open limit switch LSZ is provided such as shown in Fig. 18. With this set-up, the valve 4991) is opened and the valve 499a is closed so that the delayed action in shifting the valve 353 delays the ow of fluid through the pipe 137 to both the cylinder 75 and the rock bar cylinder 125. The extent of the delayed action of uid passing through the pipe 137 may be regulated by ad- 5 justment of the throttle valve 452 which controls the rate of shifting movement of the valve 353 toward the left. In this latter case the normally open limit swtich LSZ is arranged so that the bracket 408a on the rock bar 20 actuates the limit switch LSZ slightly before the base circle of the master cam rotates into contact with the follower roller 101 so that at count-out of the counters 481 and 482, the separating movement between the grinding wheel 34 and the work piece 27 will be initiated so as to cause a simultaneous movement of the rock bar 20 and the feed piston 76 to separate the cam being ground from the grinding wheel when the base circle of the cam is in operative engagement with the grinding wheel.

The cycle start valve 410 (Figs. 6 and 16) is a piston type valve comprising a valve stem 411 having a pair of spaced integral valve pistons 412 and 413 which form a valve chamber 414. The valve 410 is normally held in an uppermost position by means of a compression spring 415. A cycle start lever 416 is mounted on the upper end of a vertical shaft 417 supported in bearings 418 and 419. The lower end of the shaft 417 is provided with a short arm 420 which is provided with an oiset stud 421 which is arranged to engage a frustoconicallly shaped head 422 mounted on the upper end of a plunger 423 for actuating the valve stem 411.

In order to facilitate rendering the hydraulic table traverse mechanism inoperative during the grinding of either a main bearing or an eccentric on the cam shaft being ground, a control valve 555 is provided which is normally held 'in an uppermost position by a compression spring 556. The valve 555 is actuated by an adjustable dog 557 mounted on the table 11. The valve 555 is connected with valve 455 by a pipe 553, When the dog 557 moves into the position illustrated in Fig. 16, it depresses the valve 555 and also actuates and closes a limitv switch LSS. One of the contactors of limit switch L88 closes a circuit to energize solenoid S1 to shift valve 455 into the position illustrated in Fig. 16 so that fluid under pressure passing through the valve 455 passes through the pipe 558 and through the valve 555 into a pipe 559. Fluid under pressure passing through the pipe 559 is conveyed to the right hand end chamber of an interlock valve 560 to move the valve 560 into a left hand end position against the compression ofy a spring 561. The valve 560 in the position illustrated in Fig. 16 is arranged to prevent passage of uid under pressure from the table reversing valve 380 to the end chambers of the table reverse control valve 350. The valve 560 remains in the position illustrated until the solenoid S1 is deenergized at cut-out of the electric counter previously described. When the solenoid S1 is deenergized fluid may then exhaust from the right hand end chamber of the valve 569, through the valve 555, through the valve 455 and out through the exhaust pipe 461. The released compression of spring 561 then shifts the valve 560 toward the right so that lluid under pressure may pass from the valve 380, through the pipe 569, through a chamber in the valve 560, through the pipe 376 into chamber 374 to shift the valve 351 toward the left so that fluid under pressure entering the valve chamber 364 of the valve 350 passes through the pipe 363 into cylinder chamber 359 to move the table 11 toward the left.

Fluid under pressure passing through the valve 555 and through the pipe 559 also passes through a valve 565 to the left hand end chamber of an interlock valve 566 to move the valve 566 toward the right against the compression of a spring 567. In the position of the valve 566 (Fig. 16) uid under pressure passing through the pipe 559 passes through a chamber in the valve 566 and through the pipe 109 to move the piston 105 toward the right thereby engaging the hand traverse clutch to facilitate a manual spark splitting operation, that is, a manual shifting of the table 11 during the shoulder grinding operation to equalize the side grinding action of the grinding wheel as it is fed toward the work axis. At the same time tiuid under pressure passing through the chamber in the valve 566 passes through the pipe 295 through the valve 296, into the cylinder chamber 297 to move the piston 299 toward the right (Fig. 16) so as to stop the wheel spindle reciprocation during the grinding of a main bearing or a pump eccentric.

In case the main bearing or eccentric on the cam shaft being ground does not have opposed shouldered faces to be ground, the valve 565 may be closed manually to cut ol the passage of uid to the valve 566 and also through the pipe 109 thereby allowing the hand traverse clutch to remain disengaged and the wheel spindle reciprocation in operation during the plunge-cut grinding operation. In setting up the machine for such an operation, the valve 565 is preferably closed when the valve 555 is in an uppermost position so that fluid may exhaust from the cylinder and the cylinder 298, through the valve 555 and through an exhaust pipe 56S.

During movement of the table toward the right when successive cams aregbeing ground Huid under pressure from the reversing valve 380 passes through a pipe 569 into the right hand end chamber of the Valve 566 which serves together with the compression of the spring 567 to shift and hold the valve 566 in a left hand end position. In this position of the valve 556, a pipe 570 connected be- `geraete tween the valve 280 and the valve 566 allowsfluid under pressure to pass into the cylinder chamber 297 at the start of a grinding wheel truing operation to stop Wheel spindle reciprocation during the truing operation. When the reversing valve 380 is shifted into the reverse position fluid under pressure passing through the pipe 569 also passes through the pipe 108 into the cylinder 105 to hold the manually operable traverse clutch disengaged during the entire movement of the table 11 toward the right in grinding successive cams. Fluid under pressure passing through the pipe 569 also passes into the left hand end chamber of the valve 560 to supplement the compression of the spring to hold the valve 560 in a right hand end position during the entire movement of the table 11 toward the right so that uid under pressure passing through the pipe 354 enters an end chamber 355 in the valve 351D to shift the valve 350 into a right hand end position and to maintain it in this position during the entire movement of the table toward the right so that fluid under pressure is passed hrough the pipe 357 into the cylinder chamber 358.

The compression springs 561 and 567 in the valves 560 and valves 566 respectively serve to hold the valves against pressure in the opposite directions when the dog 557 rides over the stem of the valve 555 during the traversing movement of the table 11 in passing the eccentric or main bearing on the shaft which has been previously ground.

A truing apparatus control valve 580 mounted on the front of the machine hase is normally held in an uppermost position by a compression spring 581. An adjustable table dog 532 carried by the table 11 is arranged to depress the valve 53) when the table moves toward the left after grinding a main bearing or pump eccentric. When the valve 581 is in a depressed position fluid under pressure from the reversing valve 3311 passing through the pipe 376 passes through a chamber in the valve 580 through a pipe 533 through a valve 584, through a pipe 535, through the selector valve chamber 487 of the selector valve 285, through the pipe 268 into an end chamber formed at the right hand end of the valve 255 to shift the valve toward the left so as to initiate a truing operation as above described.

A pipe 586 is connected between the pipes 376 and 585. A manually operable valve 587 is provided in the pipe 536. As shown in the diagram in Fig. 16 the valve 587 is closed and the valve 534 is opened so that actuation of the truing apparatus will occur when the valve 580 is actuated by the table dog 532. This operation'will occur depending upon the position of the dog 582 either after a main bearing or pump eccentric has been ground.

A table indexing mechanism is provided for successively locating the table 11 in predetermined positions for grinding successive cams on a cam shaft to be ground. This mechanism may comprise a table stop lug 430 (Figs. 6, 7 and 16) iixedly mounted on a pivotally mounted lever 431 which is supported by a stud 432. The stud 432 is supported in fixed relation with the base 10. A compression spring 433 serves normally to exert a pressure tending to hold the stop lug 43) in an uppermost position. The stop lug 43th is arranged in the path of a plurality of adjustable table dogs 434 carried by the table 11 intermittently and successively to locate the table in positions for grinding cams.

A hydraulically operated mechanism is provided for rocking the arm 431 to shift the stop lug 431B out of the path of table dogs 434 to facilitate an indexing movement. This mechanism may comprise a vertically arranged plunger 435 (Figs. 6 and 16) which is provided with a lip 436 which is arranged to engage a portion of the lever 431. A hydraulic cylinder 437 contains a slidabiy mounted piston 433 which is connected to one end of a piston rod 439. The other end of the piston rod 439 is connected to the plunger 435 to move it vertically in a manner to be hereinafter described. A compression spring 433 serves normally to hold the stop lug in an upper most position in the path of the table dogs 434 When uid under pressure is' passed through a pipe 441 it enters a cylinder chamber below the piston 43S anc assists the spring 441! in holding the plunger 435 in ar uppermost or operative position. When iiuid under pres sure is passed through a pipe 442 into a cylinder cham ber formed at the upper end of the cylinder 437, the pistor 438 together with the piston rod 439 and the plunger 435 moves downwardly to rock the lever 431 in a counter clockwise direction thereby swinging the stop lug 43( out of the path of the table dogs 434.

A slow-down mechanism is provided whereby the indexing movement of the table 11 may be slowed dowr just before the table -dog 434 moves into engagement with the stop lug 430. This mechanism comprises a vertically arranged plunger 445 which slides within a central bore within the plunger 435. The plunger 445 is arranged to actuate a piston type valve 446 (Figs. 6 anc 16) which comprises a valve stem 447 having a pair o1 spaced valve pistons 448 and 449 formed integrally therewith so as to form a valve chamber 450. A compressior spring 451 serves normally to hold the valve stem 447 together with the plunger 445 in an uppermost position with its upper end positioned in the path of the table dogs 434.

A cycle control valve 455 is provided for controlling the admission to and exhaust of uid from the cylinder 437. The valve 455 is a piston type valve comprising a valve stem 456 having a plurality of valve pistons formed integrally therewith to form a plurality of spaced valve chambers 457, 453 and 459 (Fig. 16). A compression spring 460 serves normally to exert a pressure tending to move the valve stem 456 into a right hand end position. A solenoid S1 is provided which when energized serves to shift the valve stem 456 into a left hand end position as illustrated in Fig. 16. In the position of the parts illustrated in Fig. 16 fluid within the chamber at the upper end of the cylinder 437 may exhaust through the pipe 442 into the valve chamber 459 and out through an exhaust pipe 461. In this position of the parts fluid under pressure from the pressure pipe line enters the valve chamber 458 and passes through the pipe 441 into the cylinder chamber at the lower end of the cylinder 437 to supplement the spring 440 so as to hold the piston 438 together with the plunger 435 in an uppermost position. At the same time fluid passing through the pipe 441 is conveyed to the valve 446 but is blocked by one of the valve pistons.

When the solenoid S1 is deenergized after a grinding cycle, the valve stem 456 moves toward the right so that uid from the pressure pipe 90 entering the valve chamber 453 passes through the pipe 442 into the upper cylinder chamber in the cylinder 437 to cause a downward movement of the piston 43S together with the piston rod 439 and the plunger 435 thereby rocking the lever 431 (Fig. 6) in a counter-clockwise direction to withdraw the stop lug 430 out of the path of the table dogs 434 thereby initiating a table indexing movement to position the table 11 for grinding the next cam on the cam shaft to be ground.

The table 11 is indexed intermittently toward the right to grind successive cams on the cam shaft 27. After the last cam on the shaft has been ground, the table 11 continues its movement toward the right until the reversing dog 383 engages the detent 385 to shift the valve 330 into a reverse position. Before the valve 381i is reversed, a dog 333 on the table 11 actuates a limit switch LSS to open the normally closed contacts thereof and to close the normally open contacts thereof, so that when the positioning cam 4119 opens the normally closed limit switch L54, the work `driving motor will stop with the cam shaft 27 in a predetermined loading position.

A push button start switch 470 is provided for starting an electric motor 474 which drives the uid pumps 85 and, 8,6 and at the rsame time serves to start a motor 475 to drive a coolant fluid pump (not shown). A push button stop switch 471 is provided to facilitate stopping the motors 474 and 475 when desired.

A push button start switch 472 is provided for starting the grinding wheel driving motor 35. A push button stop switch 473 is provided to facilitate stopping the moor 35 when desired.

A start switch 476 is provided for rendering the control mechanisms of the machine operative and a stop switch 477 is provided for stopping the operation of the machine at any time when desired. A pivotally mounted :ontrol lever 478 is provided for actuating the start switch 476 and the stop switch 477. The actuation of the lever 478 in a clockwise direction (Fig. 17) serves to :lose the start switch 476 to energize a relay switch CE2. A holding circuit is set up through one of the contactors of the relay switch CRZ to maintain relay switch CRZ energized. The function of the release switch CR2 will be hereinafter described.

It is desirable to provide a work driving mechanism arranged so that the work piece may be initially ground while rotating at a relatively fast speed after which the speed is automatically reduced to a slower final speed. The work driving motor 145 is preferably a two-speed motor in which the high speed windings are utilized to facilitate stopping the motor with the work piece or cam shaft 27 in a predetermined position to facilitate loading. The motor 145 is controlled by a fast speed relay switch FH to facilitate rotating the work at a relatively fast speed, and a relay switch SH to control the slow speed of the motor 145 tor a iinal grinding speed. A pair of electric `counters 431 and 452 are provided, the counter 481 serving to control the duration of the first speed of the motor, and counter 482 serving to control the duration of the iinal grinding speed of the motor 145 in a manner to he hereinafter described.

A selector switch 48) is provided which in the position illustrated in Fig. 17 serves to render both of the counters 481 and 482 operative so that the motor 145 drives the cam shaft 27 through a predetermined number of rotations at a rough grinding speed after which the speed of the motor 145 is automatically reduced to a finish grinding speed, the duration of which is controlled by the counter 482. rEhe selector switch 430 as illustrated is positioned with contacts B closed so that both the counters 431 and 452 are rendered operative.

If it is desired to operate the machine as a rough grinding machine, the selector switch 486 is shifted in a counterclockwise direction (Fig. 17) to close the contactor F which serves to render the counter 482 inoperative and the counter 431 operative to control the duration of the rough grinding operation, the speed of said motor being controlled in this case by relay switch FH. lf it is desired to operate the machine as a finish grinding machine, the selector switch 481i may be shifted in a clockwise direction (Fig. 17) to close the contactor S which serves to render the counter 481 inoperative and the counter 482 operative to control the duration of the finish grinding operation during which the speed of the motor 145 is controlled by the relay switch SH.

A manually operable selector switch 485 is provided which as shown in Fig. 17 serves to render both of the counters 481 and 432 operative. lf it is desired to cut out both of the counters 481 and 482, the switch 455 may be shifted in a counterclockwise direction, after which a manually operable start switch 486 may be operated to control the motor 145 manually to facilitate setting up the grinding machine.

The cam grinding machine is made ready for a grinding operation by turning the electric power on, after which a cam shaft 27 is loaded into the machine. The switch 479 is closed to start both the hydraulic pump motor 474 and the coolant iiuid pump motor 475. The switch 472 is closed to start the wheel driving motor 35. The normally closed limit switch LS4 is opened by the positioning cam 409. The limit switch LS4 is connected in series with the normally open contacts limit switch LSS operated by the table dog 383 which operates when the table indexes to position the last cam on the cam shaft 27 into an operative position for grinding. The normally closed limit switch LS6 is connected in series with the limit switch LS1 to prevent actuation of the valve 455 and thereby prevent movement of the table 11 toward the left before the rock bar 20 rocks to an inoperative position as illustrated in Fig. 16. The limit switch LS3 (normally closed) is held open by the rock bar 20 when in an inoperative position. During each oscillation of the rock bar 20 when the rock bar is in an operative position, the normally closed contacts of the limit switch LS2 or LS1@ open giving a count impulse to either of the electric counters 481 and 482. The normally closed limit switch LS1 or LSS is closed so that the solenoid S1 is energized and the clutch coils CCH1 and CCH2 of the counters 481 and 482 hold the solenoid S1 energized through the contacts LCI or LCZ until count-out. When a table dog 434 depresses the plunger 445 the limit switch LS1 is opened. When the solenoid S1 is energized, the valve 455 is moved into a left hand end position so as to allow fluid under pressure to pass through the lower chamber of the cylinder 437 and also to the valve 446 which is now blocked. The table stop dog 425 has rotated the cycle start-stop lever 416 in a counter-clockwise direction to depress the valve 410 so as to cut olf fluid between the valves 352-353 and the valves 380 and 351. The rocking bar 20 and the wheel slide 311 are held in inoperative positions by fluid under pressure through the valves 352 and 353, 400 and 410. The wheel slide swivel cylinder 197 is balanced so that both sides thereof are open to the exhaust. The table stop lever 431 together with the stop lug 430 is held in an upper or operative position by fluid under pressure passing to the lower chamber in the cylinder 437 from the valve 455. The reversing lever 382 is in position for a left hand traversing movement of the table 11 but the table 11 is held stationary, since there is no pressure on either side of the valve 351 which is held in a centered position by a pair of balanced compression springs. The valves 352 and 353 are normally held in a left hand end position by compression springs.

In the position of the valves 352 and 353 (Fig. 16) iiuid under pressure from the pipe 911 enters a valve chamber 486 in the valve 352 and passes through a passage 487 into a valve chamber 488 in the valve 353 and passes through the pipe 137 into the cylinder chamber 133 to move the rock bar piston 26 toward the right into the position illustrated in Fig. 16 to rock the rock bar 29 to an inoperative position. During this movement fluid may exhaust from the cylinder chamber 139 through the pipe 140 into a valve chamber 489 in the valve 352. through a central passage 4911 in the valve 352 into a valve chamber and out through an exhaust pipe 496.

Operation Assuming the machine is set up for iirst grinding a main bearing or pump eccentric having opposed shouldered faces, after which the grinding wheel is trued and successive cams are ground to a predetermined size and contour.

The start switch 472 (Fig. 17) is closed to start the grinding wheel driving motor 35. The switch 470 is closed to start the motor 474 which drives the fluid pumps and 86, and also to start the coolant driving motor pump 475. The lever 478 is then rocked in a clockwise direction (Fig. 17) to close a circuit thereby energizing a relay switch CRZ and to set up a holding circuit to maintain the switch CE2 energized. One set of contactors of the relay switch CR2 serves to render a circuit operative as will be hereinafter described. In a loading position dog 557 depresses valve 555 and also closes limit switch LSS to energize solenoid S1. The closing of switch LSS 

